Open Data supplied by Natural Environment Research Council (NERC)

Niskin Bottle

The Niskin bottle is a device used by oceanographers to collect subsurface seawater samples. It is a plastic bottle with caps and rubber seals at each end and is deployed with the caps held open, allowing free-flushing of the bottle as it moves through the water column.

Standard Niskin

The standard version of the bottle includes a plastic-coated metal spring or elastic cord running through the interior of the bottle that joins the two caps, and the caps are held open against the spring by plastic lanyards. When the bottle reaches the desired depth the lanyards are released by a pressure-actuated switch, command signal or messenger weight and the caps are forced shut and sealed, trapping the seawater sample.

Lever Action Niskin

The Lever Action Niskin Bottle differs from the standard version, in that the caps are held open during deployment by externally mounted stainless steel springs rather than an internal spring or cord. Lever Action Niskins are recommended for applications where a completely clear sample chamber is critical or for use in deep cold water.

Clean Sampling

A modified version of the standard Niskin bottle has been developed for clean sampling. This is teflon-coated and uses a latex cord to close the caps rather than a metal spring. The clean version of the Levered Action Niskin bottle is also teflon-coated and uses epoxy covered springs in place of the stainless steel springs. These bottles are specifically designed to minimise metal contamination when sampling trace metals.

Deployment

Bottles may be deployed singly clamped to a wire or in groups of up to 48 on a rosette. Standard bottles have a capacity between 1.7 and 30 L, while Lever Action bottles have a capacity between 1.7 and 12 L. Reversing thermometers may be attached to a spring-loaded disk that rotates through 180° on bottle closure.

Data Originator

NB Users interested in nutrient data should be aware that there are continuous surface nutrient measurements for each RRS Challenger cruise included in the underway data set.

Sampling strategy and methodology

Water samples were collected from either the ship's non-toxic pumped seawater supply or from water bottles on the CTD rosette. The samples were filtered immediately through tared GF/F filters and both the filters and filtrate were stored frozen until analysed back at the laboratory.

The filtrates were analysed using manual colorimetric methods (Parsons et al., 1984) for orthophosphate. Total phosphate was determined by the same method on sample aliquots in which the organic phosphorous had been oxidised to phosphate. Further details are given in Ormaza-Gonzalez and Statham (1996).

LOIS River-Atmosphere-Coast Study (LOIS - RACS)

Introduction

The Land-Ocean Interaction Study (LOIS) was a NERC research programme designed to study processes in the coastal zone. The Rivers, Atmosphere and Coasts Study (RACS) was a major component of LOIS that looked at land-sea interactions in the coastal zone and the major exchanges (physical, chemical and biological) between rivers and estuaries and the atmosphere. The study focused on the east coast of the UK from the Wash to the Tweed.

RACS included several sub-components

BIOTA - A study of salt marshes of the Humber and Wash

RACS (A) - An atmospheric chemistry study looking at air mass changes from the Wash into East Anglia

RACS (C) - A study of the estuaries, coasts and coastal waters between Great Yarmouth and Berwick upon Tweed.1. The coastal oceangraphic survey2. The Humber estuarine study3. The Tweed estuarine study4. The Holderness experiment

RACS (R) - A study of rivers that drain into the North Sea

RACS (A) was coordinated by the University of East Anglia and RACS (C) by the Plymouth Marine Laboratory.

RACS (A)

The bulk of the RACS (A) data set was collected during two field campaigns in the winter (October/November) of 1994 and the summer (May/June) of 1995. During these campaigns data were collected continuously from the University of East Anglia Atmospheric Observatory at Weybourne on the north Norfolk coast. An instrumented vessel was stationed offshore to provide a second sampling site to allow changes in a given air mass to be monitored. The Imperial College Jetstream research aircraft made one flight during each campaign to provide a link between the two surface stations. The Jetstream made four additional flights in 1996 and 1997.

RACS (C)

The coastal oceanographic survey

The coastal oceanographic data set was collected during a series of 17 RRS Challenger cruise legs. Most cruises covered two survey grids. One from Great Yarmouth to the Humber designed around the distribution of the sandbanks and a second simple zig-zag grid from the Humber to Berwick on Tweed. A large number of anchor stations, usually over one or two tidal cycles, were worked in the area of the Humber mouth or the Holderness coast.

The Humber estuarine study

The Humber estuarine data set was collected during a series of 33 campaigns on the Environment Agency vessels Sea Vigil and Water Guardian in the Humber, Trent and Ouse river systems at approximately monthly intervals between June 1993 and December 1996. Each campaign consisted of two or three one-day cruises. The tracks covered the estuary from the tidal limits of both Trent and Ouse to Spurn Point. Instrumental and sample data are available from a series of fixed stations that were sampled during every campaign.

The Tweed estuarine study

The Tweed estuarine data set was collected during a series of 13 campaigns using RV Tamaris in association with a rigid inflatable vessel at approximately monthly intervals between July 1996 and July 1997. Each campaign covered the tidal reaches of the River Tweed.

The Holderness experiment

The Holderness Experiment was designed to monitor the process of sediment transport along the Holderness coastline. It consisted of three moored instrument deployments during the winters of 1993-1994, 1994-1995 and 1995-1996. Mooring platforms were deployed at eight stations along two lines off the Holderness coast. A northerly and a southerly line of four stations each were used (N1 - N4 and S1 to S4) with the lowest numbers being inshore. Both lines were approximately perpendicular to the coast, although the S4 station lay to the south of the S line, off Spurn Head.

Data Activity

University of Plymouth Institute of Marine Studies (now University of Plymouth, School of Geography, Earth and Environmental Sciences)

Country of Organization

United Kingdom

Originator's Data Activity Identifier

CH108C_CTD_CTD27

Platform Category

lowered unmanned submersible

BODC Sample Metadata Report for CH108C_CTD_CTD27

Sample reference number

Nominal collection volume(l)

Bottle rosette position

Bottle firing sequence number

Minimum pressure sampled (dbar)

Maximum pressure sampled (dbar)

Depth of sampling point (m)

Bottle type

Sample quality flag

Bottle reference

Comments

364443

10.00

24.40

24.50

23.60

Niskin bottle

No problem reported

364444

10.00

4.20

4.40

3.60

Niskin bottle

No problem reported

364445

10.00

1.70

2.00

1.30

General Oceanics GO-FLO water sampler

No problem reported

Please note:the supplied parameters may not have been sampled from all the bottle firings described in the table above. Cross-match the Sample Reference Number above against the SAMPRFNM value in the data file to identify the relevant metadata.